Chemistry Reference
In-Depth Information
5.5
THE BREATHING MODE
The tuning of the inner particle nanostructures could be readily controlled by
altering the system's composition and/or varying the temperature. Figure 5.9
summarizes the impact of temperature and TC loading on the MLO-based
dispersed and nondispersed systems.
SAXS investigations on both oil-free and oil-loaded MLO dispersions were
carried out in order to elucidate the structural changes of these internal nano-
structures that occur during heating-cooling processes. In the absence of oil
(
0), the MLO dispersion was measured at three temperatures in a heating-
cooling cycle (Fig. 5.10a). As discussed above, heating of the dispersion
led to structural transitions of the internal nanostructure in the order V
2
(Pn3m)
α
=
ELP. Figure 5.10a shows also that cooling the dispersion
induced the inverse order of the structural transitions without a hysteresis or
other changes after application of the heating-cooling cycles. Therefore, the
respective scattering curves of the dispersion at 25°C (cubosomes) and 58°C
(hexosomes) were found to coincide. This meant that the internal nanostruc-
ture, similar to its counterpart in the fully hydrated nondispersed phase,
depended only on the current temperature, irrespective of whether it was
reached by heating or cooling.
→
H
2
→
Addition of water plus secondary emulsifier
Reverse W/O microemulsion (L
2
)
Emulsified microemulsions
Discontinuous micellar cubic (I
2
)
Micellar cubosomes
Reverse hexagonal (H
2
)
Hexosomes
Cubosomes
Bicontinuous cubic (V
2
)
25 ºC
25 ºC
Bulk nondispersed systems
Isasomes
Figure 5.9
Formation of ISAsomes from MLO-based nanostructures.
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